Dear Jamal,
Yes we have register the said code. System was assigning code automatically to the patients. Then all of a sudden this error started popping up .
Thank you Gassim.
Yes, initially it was working fine ( <IICTH0008-24-036>), later producing the error mentioned above. Then, we increased the patient code from 3 digits to 4 digits i.e. IICTH0008-24-0036 and assigned one digit to all previously registered patients through database. This produced the same error after working fine for sometime.
If we increase the code from 4 digits to 5, then it will work again, however, I believe this is not a permanent solution.